Photopolymerizable unsaturated polyesters containing benzoin-ether,organic acid ester,organic phosphine initiators

ABSTRACT

THE INVENTION RELATES ALSO TO A PROCESS FOR THE PREPARATION OF SHAPED ARTICLES, IMPREGNATIONS, COATINGS AND THE LIKE, FROM SUCH PREPARATIONS URABLE BY UV IRRADIATION, SUCH AS MOULDING, IMPREGNATING AND COATING COMPOSITIONS, OF MIXTURES, STABLISED IN THE USUAL MANNER, OF UNSATURATED POLYESTER RESINS AND COPOLYMERISABLE, MONOMERIC COMPOUNDS AND PHOTO-INITIATORS, WHICH OPTIONALLY ADDITIONALLY CONTAIN POLYMERISATION INITATORS AND/OR METAL ACCELERATORS AND/OR PARAFFIN OR WAX OR WAX-LIKE SUBSTANCS, CHARACTERIZED IN THAT, AS THE PHOTO-INITIATOR, THE SAID OVERALL COMBINATION IS USED.   WHEREIN R1, R2 AND R3 CAN BE IDENTICAL OR DIFFERENT AND REPRESENT ALIPHATIC, CYCLOALIPHATIC, AROMATIC, ARALIPHATIC OR HETEROCYCLIC RADICALS-BUT ONE OF THE RADICALS R1, R2 OR R3 MUST ALWAYS BE AN AROMATIC RADICAL-AND THE PERCENTAGES BY WEIGHT MENTIONED RELATED TO THE TOTAL WEIGHT OF UNSATURATED POLYESTER RESIN AND COPOLYMERSIBLE MONOMERS.   R1-P(-R2)-R3   WHEREIN R1, R2 AND R3 CAN BE IDENTICAL OR DIFFERENT AND REPRESENTED ALIPHATIC, CYCLOALIPHATIC, AROMATIC, ARALIPHATIC OR HETEROCYCLIC RADICALS-BUT ONE OF THE RADICALS R1, R2 OR R3 MUST ALWAYS BEN AN AROMATIC RADICAL-AND (B&#34;) OF ORGANIC DERIVATIVES OF PHOSPHINE OF GENERAL FORMULA   R1-O-P(-O-R2)-O-R3   (A) BENZOIN-ETHERS, AND (B) A SUB-COMBINATION OF AT LEAST TWO DIFFERENT COMPOUNDS (B&#39;&#39;) ORGANIC ESTER OF PHOSPHROUS ACID OF GENERAL FORMULA   THIS INVENTION RELATES TO PREPARATIONS CURABLE BY UV IRRADIATION, SUCH AS MOULDING, IMPREGNATING AND COATING COMPOSITIONS, OF MIXTURES, STABILISED IN THE USUAL MANNER, OF UNSATURATED POLYESTER RESINS AND COPOLYMERSIBLE, MONOMERIC COMPOUNDS AND PHOT-INITATORS, WHICH OPTIONALLY ADDITIONALLY CONTAIN POLYMERISATION INITATORS AND/OR METAL ACCELERATORS AND/OR PARAFFIN OR WAX OR WAXLIKE SUBSTANCES, CHARACTRIZED IN THAT THEY CONTAIN AS THE PHOTO-INITIATOR, AN OVERALL COMBINATION CONSISTING OF:

United States Patent Qifice 3,699,022 Patented Oct. 17, 1972 ABSTRACT OFTHE DISCLOSURE This invention relates to preparations curable by UVirradiation, such as moulding, impregnating and coating compositions, ofmixtures, stabilised in the usual manner, of unsaturated polyesterresins and copolymerisable, monomeric compounds and photo-initiators,which optionally additionally contain polymerisation initiators and/ormetal accelerators and/or paraffin or wax or waxlike substances,characterised in that they contain, as the photo-initiator, an overallcombination consisting of:

(a) benzoin-ethers, and (b) a sub-combination of at least two differentcompounds of trivalent phosphorus, consisting of: (b') organic esters ofphosphorous acid of general formula PO-Rz O-Ra (I) wherein R R and R canbe identical or different and represent aliphatic, cycloaliphatic,aromatic, araliphatic or heterocyclic radicals-but one of the radials RR or R must always be an aromatic radical-and (b) of organic derivativesof phosphine of general formula Ra (II) wherein R R and R can beidentical or different and represent aliphatic, cycloaliphatic,aromatic, araliphatic or heterocyclic radicals-but one of the radials RR or R must always be an aromatic radical-and the percentages by weightmentioned relate to the total weight of unsaturated polyester resin andcopolymerisable monomers.

The invention relates also to a process for the preparation of shapedarticles, impregnations, coatings and the like, from said preparationscurable by UV irradiation, such as moulding, impregnating and coatingcompositions, of mixtures, stablised in the usual manner, of unsaturatedpolyester resins and copolymerisable, monomeric compounds andphoto-initiators, which optionally additionally contain polymerisationinitiators and/or metal accelerators and/or paraffin or wax or wax-likesubstances, characterised in that, as the photo-initiator, the saidoverall combination is used.

BACKGROUND OF THE INVENTION (1) Field of the invention This inventionrelates to preparations curable by UV irradiation, such as moulding,impregnating and coating compositions, of mixtures, stabilised in theusual manner,

of unsaturated polyester resins and copolymerisable, monomeric compoundsand photo-initiators which optionally additionally containpolymerisation initiators and/or metal accelerators and/or paraifn orwax or wax-like substances, characterised in the they contain, as thephotoinitiator, an overall combination consisting of:

(a) 0.1 to 4% by weight of benzoin-ethers, and

(b) a sub-combination of at least two different compounds of trivalentphosphorus, consisting of:

(b') 0.6 to 20% by weight of organic esters of phosphorous acid ofgeneral formula wherein R R and R can be identified or diiferent andrepresent aliphatic, cycloaliphatic, aromatic, araliphatic orheterocyclic radicals-but one of the radials R R or R must always be anaromatic radicaland (b") 0.05 to 2% by weight of organic derivatives ofphosphine of general formula Ra (II) wherein R R and R can be identicalor dilferent and represent aliphatic, cycloaliphatic, aromatic,araliphatic or heterocyclic radicals-but one of the radials R R or Rmust always be an aromatic radical-and the percentages by weightmentioned relate to the total weight of unsaturated polyester resin andcopolymerisable monomers.

The invention relates also to a process for the preparation of shapedarticles, impregnations, coatings and the like, from said preparationscurable by UV irradiation, such as moulding, impregnating and coatingcompositions, of mixtures, stabilised in the usual manner, ofunsaturated polyester resins and copolymerisable, monomeric compoundsand photo-initiators, which optionally additionally containpolymerisation initiators .and/or metal accelerators and/or paraffin orwax or wax-like substances, characterised in that, as thephoto-initiators, the said overall combination is used.

(2) Description of the prior art German displayed specifications1,297,269, 1,694,149, 1,902,930 and the Austrian Pat. 286,642 havedescribed moulding compositions and coating compositions of mixtures,stabilised in the usual manner, of unsaturated polyesters, andcopolymerisable monomeric compounds, which contain benzoin-ethers andmetal accelerators or benzoin-ethers of secondary alcohols andoptionally additionally a peroxide catalyst and/or acid esters ofphosphoric acid and/ or metal accelerators and benzoin-ethers of primaryalcohols respectively and copper compounds meaning such copper compoundsbeing described in the US. Pats. 3,028,360 and 3,360,589, andbenzoin-arylethers respectively.

The known systems can be cured both by the action of high energyradiation from, for example mercury vapor high pressure lamps, and bythe action of radiation of less high energy, for example undersuper-actinic radiation from fluorescent lamps which possess a coatingof fluorescent substances which emit blue-violet light and rays in thelonger-wavelength UV, for example in the range of 3000 to 5800 A.

When using these benzoin-ethers as sensitisers, it is possible tophotopolymerise mixtures of unsaturated polyesters with unsaturatedvinyl compounds, such as styrene, at room temperature in a relativelyshort time.

Here a content of benzoin-ethers of about 2% by weight, relative to themixture, is necessary to achieve adequate activity. However, afterirradiation under mercury vapor high pressure lamps these mixtures showan intense yellow coloration which does not fully disappear again evenat the end of several days.

German displayed specification 1,934,637 already discloses unsaturatedpolyester preparations curable by irradiation which contain anunsaturated polyester with a hydroxyl number of 55 to 75, acopolymerisable monomer, and stabiliser combination of 200 to 800 partsper million of an alkyl phosphite or aryl phosphite and 10 to 50 partsper million of a copper salt of organic acids; in addition, 0.1 to ofbenzoin or of a benzoin substituted in a-position by a C -C alkylradical are used as a photo-initiator. Curing takes place by irradiationwith light of wavelengths 2500 to 4000 A. These polyester preparationsshow improved storage stability in the dark, but do not show a shortenedcuring time relative to comparable photopolymerizable polyesterpreparations stabilised in other ways.

It is the task of the present invention to improve unsaturated polyesterpreparations which are curable by UV irradiation in at least fourdirections conjointly relative to the state of the art, namely:

(1) To improve, quite considerably, the dark storage stability at roomtemperature and at elevated temperatures up to about 60 C.

. (2) To increase the polymerisation speed quite considerably, so thatthe UV-radiation time can be correspondingly shortened.

(3) To reduce the discoloration of the cured polyester preparation byreducing the sensitiser concentration used, whilst having a relativelyshort irradiation time.

(4) To obtain a non-tacky surface when light-curing such air-dryingpolyester resins that contain proportional amounts of B,'y-unsatu.ratedether-alcohols.

These tasks are solved, surprisingly, through benzoinethers in certaincombinations with compounds of trivalent phosphorus being contained inthe unsaturated polyester preparation.

SUMMARY OF THE INVENTION When employing the overall combinationconsisting of- (a) and (b) ((b') and (b")), a synergistic efiectsurprisingly manifests itself, which causes extremely shortpolymerisation times on UV irradiation.

The extraordinary high reactivity of the preparations according to theinvention makes it possible to reduce the content of benzoin-ethersconsiderably relative to the known preparations, for comparable curingtimes, or alternatively considerably to shorten the curing times forcomparable content of benzoin-ethers.

' The high reactivity of the preparations according to the inventionpermits rapid curing of thin layers, in particular also under the actionof ultra-violet and visible radiation of comparatively low energyfluorescent lamps with an emission of about 3000 to 5800 A.; this isparticularly advantageous when photo-curing coatings based onunsaturated polyester resins.

By unsaturated polyester resins, there are understood the customarycondensation products (compare Johan Bjorksten, Polyesters and TheirApplications, Reinhold Publishing Corporation, New York, 1956, pp.21-155), 'which are obtained by polycondensation from c p-unsaturateddicarboxylic acids and/ or their anhydrides with polyhydric alcoholsemployed in a molar excess. As 11,5- unsaturated dicarboxylic acids itis for example possible to use: Maleic acid, maleic anhydride, fumaric,itaconic, citraconic, mesaconic and aconitic acid, and halogenatedacids, such as for example chloromaleic acid.

. A part of the a, 8-unsaturated dicarboxylic acids can here bereplaced, in a manner which is in itself known, by saturateddicarboxylic acids, for example o-phthalic, isophthal c and terephthalicacid, tetrahydro hthalic and hexahydrophthalic acid, tetrachlorophthalicacid, hexachlorendomethylene-tetrahydrophthalic acid,endomethylene-tetrahydrophthalic acid, adipic and sebacic acid anddimerised linoleic acid and soya oil fatty acid or their anhydrides.

lPossible polyhydric alcohols are preferably dihydric alcohols, forexample ethylene glycol, propanediol-1,2, butanediol-1,3,butanedio1-1,4, diethylene glycol, dipropylene glycol and their higherhomologues, neopentylglycol, 2,2,4-trimethylpentanediol-1,3,pentylglycol, hydroxyalkylated bisphenols, hydrogenated bisphenol, anddimethylolcyclohexane. However, trihydric and polyhydric alcohols, suchas glycerol, trimethylolethane, trimethylolpropane and pentaerythritolcan also be conjointly used as a constituent.

The unsaturated polyester resins built up from these raw materials areknown to suffer from the disadvantage of forming a tacky surfaceon'curing in the presence of atmospheric oxygen. If value is attached toair-drying properties of the polyester resin, c p-unsaturatedetheralcohols must be conjointly used as a replacement for thepolyhydric alcohols, as described in the German displayed specification1,024,654 and in the US. Pat. 2,852,487. As examples, there may bementioned: The monoallyl-ether and monomethallyl-ether of ethyleneglycol, of propanediol-1,2, of butanediol-1,3 and butanediol-1,4, ofglycerol, of trimethylolpropane and trimethylolethane, and ofpentaerythritol, as well as diallyl-ethers and the correspondingmethallyl-ethers of glycerol and of trimethylolethane, oftrimethylolpropane and of pentaerythritol. Here, those 00,13-unsaturated ether-alcohols can especially be used which contain at leasttwo a,fl-unsaturated ether groups, such astrimethylolpropane-diallyl-ether, tnimethylolethane-diallylether andpentaerythritol-triallyl-ether.

Suitable copolymerisable vinyl compounds that are present individuallyor in mixture in amounts of 20 to 45% by weight relative to the mixtureof unsaturated polyester resin and copolymerizable monomers (compare forexample: Bulletin 1P8, July 1961, Amoco Chemical Corporation, with titleThe Elfect of Resin Ingredients on the Properties of IsophthalicUnsaturated Polyesters, pp. 5-19), are, for example styrene,vinyltoluene p-tert.- butylstyrene, divinylbenzene, vinylacetate,vinylpropionate, acrylic acid esters, methacrylic acid esters, methylacrylate, ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate,methyl methacrylate, ethylene glycol dimethacrylate and its higherhomologues, diethylene glycol dimethacrylate and triethylene glycoldimethacrylate. As allyl compounds, it is for example possible to use:Diallyl phthalate, diallyl maleate, diallyl fumarate, triallylcyanurate.

The moulding, impregnating and coating compositions are stabilised byadding customary inhibitors, for example p-benzoquinone,2,5-di-tert.-butylbenzoquinone, hydroquinone, tert.-butyl-pyrocatecholor toluylhydroquinone, further on copper compounds, for example coppernaphthenate, in the known amounts as described for example, in the bookKirk-Othmer Encyclopedia of Chemical Technology, IntersciencePublishers, New York, 1969, second edition, vol. 20, pp. 822-825.

Examples for the sensitisers (a) to be used in the overall combination(a) and (b) ((b') and (b")) are the benzoin-ethers of the followingalcohols: Methanol, ethanol, propanol-l, propanol-2, butanol-2,pentanol-Z, cyclohexanol, n-butanol, iso-butanol, Z-methyl-l-pentanol,2-methylpentanol-3, primary and secondary octanol, Z-ethylhexanol,n-nonanol, n-dodecanol, 6-dodecanol, lauryl alcohol, myristyl alcohol,stearyl alcohol, 2-chloropropanol-l, 3-bromopropanol-1,2,2-dichloropropanol-l, 1-chloropropanol-2, abietyl alcohol andtetnahyd-roabietyl alcohol. Amongst the mono-alcohols with an ether-likebond, those compounds which possess primary alcoholic hydroxyl groupsare preferred. However, the monoalcohols with secondary and tertiaryalcoholic hydroxyl groups can also be used. In addition to the saturatedalcohols, the unsaturated alcohols are also suitable. Individually, thefollowing examples may be mentioned: u,fl-unsaturated alcohols, such asallyl alcohol, methallyl alcohol, ethallyl alcohol, chlorallyl alcohol,crotyl alcohol, phenylallyl alcohol, methylvinylcarbinol, and theunsaturated fatty alcohols which are obtained by selective hydrogenationof unsaturated fatty acids.

Examples for benzoinarylethers (a) used for the overall combination (a)and (b) ((b') and (b")) are the benzoin-ethers of benzophenol, 2-cresol,3-cresol, 4-cresol, 3,4-dimethylphenol, 2,6-diethylphenyl,4-tert.-butylphenol, 2. methoxyphenol, 4 methoxyphenol, 2 chlorophenol,4-chlorophenol, 2,6-dichlorophenol, 2,4,6-trichlorophenol, naphthol-l,naphthol-2 and 2,2-bis-(4-hydroxyphenyl)- propane (bisphenol A).

The preparations according to the invention contain the benzoin-ethers(a) which have been mentioned, individually or mixed with one another,in amounts of 0.1 to about 4% by weight, perferably 0.1 to about 1.5% byweight, in combination with compounds of trivalent phosphorus (b) ((b')and (b")).

Possible esters of phosphorous acid (b'), which contain at least onearomatic radical, are triphenyl phosphite, trip-toluyl phosphite,tri-nonylphenyl phosphite and didecylphenyl phosphite.

Possible organic derivatives of phosphine (b") which contain at leastone aromatic radical are for example:

triphenylphosphine, tri-p-toluyl-phosphine, diphenylmethyl-phosphine,diphenyl-ethyl-phosphine, diphenylpropyl-phosphine,dimethyl-phenyl-phosphine, diethylphenyl-phosphine,dipropyl-phenyl-phosphine, divinylphenyl-phosphine,divinyl-p-methoxyphenyl-phosphine, divinyl-p-bromophenyl-phosphine,divinyl-p-toluyl-phosphine, diallyl-phenyl-phosphine,diallyl-p-methoxyphenyl-phosphine, diallyl-p-bromophenyl-phosphine anddiallyl-p-to1uyl-phosphine.

The esters of phosphorous acid (b') are present in amounts of 0.1to 20%by weight, relative to the total weight of unsaturated polyester resinand copolymerisable monomers, preferably 0.1 to 2% by weight, in themixture with the benzoin-ethers (a) and phosphines (b) which have beenmentioned.

The phosphines (b) which have been mentioned are contained in amounts of0.05 to 2% by weight, relative to the total weight of unsaturatedpolyester resin and co polymerisable monomers, in the mixture with thesaid benzoin-ethers (a) and esters of phosphorous acid (b').

DESCRIPTION OF THE PREFERRED EMBODIMENTS The most preferred overallcombinations consist of: benzoin-ethers of primary alcohols (a), estersof phosphorous acid (b') which only contain aromatic radicals, such as,for example triphenyl phosphite and/or tri-ptoluyl phosphite, andorganic derivatives of phosphine (b"), which only contain aromaticradicals, such as for example triphenyl-phosphine and/ortri-p-toluylphosphine.

At times, the conjoint use of customary polymerisation initiators(compare, for example, Johan Bjorksten, Polyesters and TheirApplications, Reinhold Publishing Corporation, New York, 1956, pp.48-51) in amounts of 0.1 to about 2% by weight, relative to the totalweight of unsaturated polyester resin and copolymerisable monomers, canbe advantageous, since the latter can stimulate polymerisation catalysisby the UV radiation itself as well as by the heat produced by the UVradiation. Suitable polymerisation initiators are, for example,tert.-butyl perbenzoate, dicumyl peroxide, benzoyl peroxide, lauroylperoxide, methyl-ethyl-ketone peroxide, methyl-isobutylketone peroxide,cyclohexanone peroxide, and ambisiso-butyronitrile.

The addition of peroxides can in some cases result in a better adhesionof the coatings to the base. Further on the conjoint use of peroxidesnamely methylethylketoneperoxide, seems advisable in all those cases inwhich the insignificant discoloring of the cured products that canappear during irradiating or in some cases during storage is wanted tobe reduced. A conjoint use of small amounts of customary acceleratorsas, for example cobalt octoate, cobalt naphthenate, zirconiumnaphthenate, dimethylanilin acetoacetic acid ester, is also possible.The application of accelerators for copolymerizing unsaturated polyesterresins and copolymerizable monomers has been described, for example inthe book Kirk-Othmer, Encyclopedia of Chemical Technology, IntersciencePublishing, New York, 1969, second edition, vol. 20, pp. 825-826.

Additional to the application of ketone peroxides metal compounds, suchas cobalt-, zirconiumand vanadiumnaphthenate, or metal chelates, such ascobaltand zirconiumacetylacetonate, can be added.

If peroxides and metal accelerators are present simultaneously thestorage stability of the compositions is rather lowered.

The conjoint use of small amounts of customary accelerators, for examplecobalt octoate, cobalt naphthenate, zirconium naphthenate,dimethylaniline, or ethyl acetoacetate, is also possible.

The addition of UV-absorbers as light stabilisers for the curedpreparations, such as derivatives of hydroxybenzophenone, of salicylicacid esters or of o-hydroxyphenylbentriazole, in the customary amountsof between 0.01 to 0.4% by weight, does not cause any significant orstill tolerable retardation of the photopolymerisation, though theabsorption of the UV-absorbers lies in the region of the long-wavelengthUV radiation required for the photopolymerisation.

These moulding, impregnating and coating compositions according to theinvention possess, in comparison to the known compositions, excellentstorage stability in the dark and are therefore outstandingly suitablefor use as stable single-component systems.

The best results are obtained by keeping a phosphite/ phosphine ratio ofabout 3:1.

To test the storage stability in the dark of the preparations accordingto the invention 61 parts by weight of an unsaturated polyester resinfrom 1 mol of maleic anhydride, 1 mol of phthalic anhydride and 2.18mols of propanediol-1,2, stabilised in the customary manner with 0.015%by weight of hydroquinone, were mixed with 39 parts by weight of styreneand mixed, in accordance with the following table, with various overallcombinations of (a) benzoin-ethyl-ether, (b') triphenyl phosphite and(b) triphenylphosphine dissolved in styrene.

TABLE 1.STORAGE STABILITY IN THE DARK Storage stability in theBenzoindark ethyl Triphenyl- Triphenyl- (60) ethei 1 phosphite 1phosphine l in days or pigmented, whereby only such pigments may be usedthat have a sufficient UV-transparence. In the process using unpigmentedpreparations for the production of closed-pore or open-pore timberpolishing lacquers, a

time or with the aid of mercury vapor high pressure lamps over a shortperiod of time. I

Because of their very short curing time, the compositions of thisinvention lend themselves to a streamlined combined curing process isadvantageous. According to method of processing adapted to the movingbelt method. this process, the coating is allowed to pre-gel under the Yaction of fluorescent lamps of comparatively low energy, MIXTURE Awhereupon a Pltllform Paraffin i Wax 5km forms 1f 100 parts by weight ofa polymerisable mixture con- PEIFFImII-COBtammg Polyester reslns f Thefinal sisting of 67 parts by weight of polyester resin (manucurmg canthen take pl l y elther through factured from 1 mol of maleic anhydride,1 mol of phthalic lrfaqlatlflll Wlth mercury Vapor [11gb P 1amps 9anhydride and 2.18 mols of propanediol-1,2) and 33 appllcatloll of heaty collventlonal Qurmg P 111 parts by weight of styrene, stabilised with0.015% by the latter case, the preparatlons accordmg to the lnveni h fhydmquinone, and having a viscosity f approx tion additionally contaln acustomary accelerator, such 1500 at 20 and an i number of 2 are dilutedas for p cobalt l are pp f to with a further 10 parts by weight ofstyrene and mixed strate which is already provided with an active primerwith 05 part by weight f a 0% strength by weight 0 1n the Journal 10,solution of paraflin (melting point 52-53 C.) in toluene, 23-31(February in order to manufacture a coating composition.

In the filled or pigmented state, the preparations according to theinvention are outstandingly suitable for the MIXTURE B manufacture offilling compositions, especially so-called roller filling compositions,which serve to smooth rough, g gi gf g g fg g z i f conporoussubstrates, such as chipboards. Suitable fillers for facturged fromp 2ofgmaleicp g l the manufacture of such filling compositions arenaturally hthalic anh dride and 3 08 mols of n g. l 2 only thoseproducts which possess adequate UV trans- 53 t b y ht f t i' g 2 gmission. Asbestos, talc, calcium sulphate, mica, ground w gi i 3 s 3% 0y gypsum (calcium sulphate), barium sulphate and highly s g an g' g o ggdisperse silica for example represent suitable fillers. 80- w an i 0 a gcalled transparent pigments or soluble dyestuffs can be a m parts ywelgo S yrepe an i used for c 010 fin g purposes part by weight of a 10%strength by weight solutlon of o For the manufacture offibre-reinforced, especially Earafiin f(mteltmg 52-53 m toluene orderglass fibre-reinforced, plastics articles using the preparao manu ac urea Goa mg Comp 081 tions according to the invention, only those processesare COMPARISON TESTS of course suitable which permit an irradiationafter shapg or after lammatmg P AS examples w Various benzoin-ethers andesters of phosphorous acid, y be me11t1011ed{ The hand P P the hmflg orvarious benzoin-ethers and triphenylphosphine, are of Contalnefs and P pand the two-sld'ed coatmg of fP' added to mixture A in theconcentrations indicated in a d a d blockhotlld P y Wlth glass fibre-remTable 2. The solutions thus obtained are cast in an approx. forcedlaminates in order to manufacture so-called con- 1 thi k layer ont aglass plate d ir di t d ith tainer sheets. Suitable reinforcingmaterials are all custh di tion from aUV lamp (El-Vak, Luminotest,Elektomary glass fibre products, such as mats, rovings andtm-Vakuum-GmbH, Berlin) at a distance of 17 cm. The varieties of wovenfabrics. After carrying out the lam1- gelling times are indicated inTable 2. 'By Way of comnating process, which 1s not tied in the usualway to a reparison, the gelling times of the mixtures free of phosphitestricted processing time or pot life, the laminate can be and of themixture free of phosphine, under the same cured by low energy radiationover a longer period of conditions, are also given.

TABLE 2 Trlphenyl- Gelling Experiment phostime in number Benzoin-etheradded Phosphrte added phine Seconds 1 0.5 benzoimnethyl other I v 2 (in0.6 triphenyl phosphite 45 a do 0.8 triphenyl phosphite-.. 45 4 (in 1.0triphenyl phosphite 40 5 1.0 benzoinmethyl ether 35 a (in 0.6 triphenylphosphite. 32 do 0.8 triphenyl phosphite. 30 do 1.0 triphenyl phosphite.30 .5 benzoinethyl ether 55 dn 0.6 triphenyl phosphite 45 (in 0.8triphenyl phosphite..- 43 dn 1.0 tnphenylphosph1te.-. 46 dn 5 0 tnphenylphosph1te 37 do 10 0 triphenyl phosphite 29 do 20 0 tr1phenylphosph1te..32 (in 0.6 trisnonylphenyl- 50 phosphite. 17 0.5 benzoinmethyl ether -40.2 18 is .da 0.6 .15 m rln 1.0 15 20 1.0 benzoinmethyl ether 0.2 12 21(in 0.6 10 22 dn 1.0 s 23 0.25 benzoinethyl ether 0.2 40 24 (in 0.6. 2525 do i 1.0' '20 26 0.5 benzoinethyl ether 0.2 V 30 27 fin 0.6 20 2;: anY 1.0 15 29 1.0 benzoinethyl ether 0.2 -18 30 do 0.6 12 31 dn L0 l Inparts by weight, relative to parts by weight of mixture A.

9 COMPARISON EXPERIMENTS 32-34 Benzoin-ethyl-ether and triphenylphosphite or benzoinethyl-ether and triphenylphosphine are added tomixture B in the concentrations indicated in Table 3. Using the sameconditions as indicated in comparison tests 1-31, the gelling. timesindicated in Table 3 are achieved.

X In parts by weight, relative to 110 parts by weight of mixture B.

As indicated in Table 2, tests 2 to 4, 6 to 8, 10 to 16 and in Table 3,test 33, the addition of 0.6 to 20% by weight phosphites relative to 110parts by weight of mixture A, respectively 110 parts by weight ofmixture B, causes a decrease of the gelling time during UV irradiation.An addition of triphenylphosphine according to Table 2, tests 17 to 31,respectively Table 3, test 34, causes a substantial decrease of thegelling time during UV irradiation, but the storage stability in thedark is also rather deteriorated.

As can be seen in Table 1 the gelling time can be shortened surprisinglyby the use of the overall combination according to the invention as wellas the storage stability in the dark can be improved.

The addition of the ingredients of the overall combination, namelybenzoin-et-hers (a), phosphite compounds (b') and phosphine compounds(b), can be ensured in any order.

In the most preferred order first the phosphite compound (b') then thephosphine compound (b") and last the benzoin-ether compound (a) isadded.

But it is substantial that the named ingredients (a), .(b') and (b") arecontained in the polyester preparation as a combination before startingthe UV irradiation.

In order that those skilled in the art can more fully understand thepresent invention, the following examples are set forth. The examplesare given solely for the purpose of illustrating the invention, andshould not be considered as expressing limitations unless so set forthin the appended claims. All parts and percentages are by weight, unlessotherwise stated.

EXAMPLES 1-1 1 Various benzoin-ethers (a), triphenyl phosphite (b') andtriphenyl phosphine (b"), in the concentrations indicated in Table 4,are added to the mixture A which has been indicated. Under the samelight exposure conditions as indicated in comparison tests 1-31, thegelling times indicated in Table 4 are achieved.

TABLE 4 h Trii h Trii eny p eny pho phos- Gelling Example phite phinetime in No. Sensitiser added 1 added 1 added 1 seconds 0.25benzoinemethylether. 0. 2 0. 1 45 2. 0.25 benzoinrnethylether. 0. 2 0. 230 3. 0.5 benzoinmethy1ether 0. 2 0. 1 30 4- 0.5 benzoinmethylether 0. 40. 2 10 5 0.25 benzoinethylether 0. 2 0. 1 30 6- 0.25 benzoinethylether0. 4 0. 2 25 7. benzoinethylether 0. 2 0. 1 16 8- 0. 4 0. 1 15 9- 0. 40. 2 10 10 d 0. 6 0. 2 9 11 1.0 benzoinethylether 0.4 0. 4 5

1 See footnote at bottom of Table 2.

EXAMPLES 12-13 Benzoin-ethyl-ether (a), triphenyl phosphite (b') andtriphenylphosphine (b), in the concentrations indicated in Table 5, areadded to the mixture B which has been indicated. Under the same lightexposure conditions as indicated in comparison tests 12l, the gellingtimes indicated in Table 5 are achieved.

TABLE 5 Trlphenyl- Triphenyl- Gelling Benzoinphosphite phosphine time inExample No. ethylether added 1 added 1 seconds 1 See footnote atbottomof Table 3.

From the gelling times indicated in Table 4 and Table 5 the describedsynergistic effect can be derived which appears when the overallcombination (a) and (b) ((b') and (b)) is being used.

This is extremely surprising so far as the esters of the phosphorousacid during conventional curing of unsaturated polyester resins andcopolymerizable monomer compounds by peroxides are known to be stronginhibitors already in small amounts.

EXAMPLES 14-20 05 part by weight of benzoin-ethyl-ether (a), 0. 6 partby weight of triphenyl phosphite (b') and 0.2 part by weight oftriphenylphosphine (b"), and additionally various conventionalpolymerisation initiators or accelerators, in the concentrationsindicated in Table 6, are added to the mixture A which has beenindicated. Under the same light exposure conditions as indicated forcomparison tests 1-31, the gelling times indicated in Table 6 areachieved.

EXAMPLE 21 1.5 parts by Weight of benzoin-ethyl-ether (a), 0.6 part byweight of triphenyl phosphite (b') and 0.2 part by weight oftriphenylphosphine (b") are added to parts by weight of the mixture Byet without addition of paraffin which has been indicated.

In order to manufacture a roller filling composition, 15 parts by weightof monostyrene, 50 parts by weight of talc, 25 parts by weight of blancfix (barium sulphate), 80 parts by weight of ground gypsum (calciumsulphate) and 1 part by Weight of highly disperse silica (Aerosil 380)are worked into this preparation, which is applied to a chipboard at acoating thickness of 250,44. After an irradiation time of 30 seconds ina UV light curing tunnel (Messrs. Behnke KG, Hamburg), the rollerfilling composition has cured and can, after cooling to roomtemperature, be rubbed down without clogging of the wet emery paper ofgrade 400 which is used.

The UV light curing channel is equipped with a high pressure burner andtwo H'I Q7 mercury vapor high pressure lamps (length of each 755 mm.,diameter 12 mm., spaced at 15 cm. from one another) of Messrs. Philips.Cooling is by air, and the irradiation distance is 20 cm.

EXAMPLE 22 1.5 parts by weight of benzoin-ethyl-ether (a), 0.6 part byweight of triphenyl phosphite (b') and 0.2 part by weight oftriphenylphosphine (b") are added to parts by weight of the mixture Awhich has been indicated, but without the addition of parafiin. Twoglass fibre mats with a customary soluble synthetic resin binder basedon polyester, and a weight per unit area of 450 g./m. are successivelylaminated, using this preparation, onto a sheet of plywood, inaccordance with the hand lay-up proces. After having impregated the matswith the above-mentioned preparation, the laminate is covered with atransparent film Which contains a release agent on the surface, and isirradiated for seconds under the mercury vapor 11 high pressure lampsdescribed in Example 21. After cooling to room temperature, the film canbe pulled off. A firmly adhering glass fibre-reinforced coating of theplywood sheet is thus obtained.

The obtained coating shows excellent transparence so that the naturalstructure of the plywood surface takes extraordinary eifect.

It has been found in a surprising manner that a such produced coatingshows essentially better mechanical properties, especially improvedbending, impact and tensile strength, than a comparably produced coatinghaving been cured by application of a conventional curing process usingperoxides as polymerization initiators and accelerators. Moreover it hasbeen found that the content of not yet copolymerized monomers in thephotopolymerized polyester resin is essentially lower immediately afterperforming the photo-polymerization than directly after performing thepolymerization in the usual manner by the use of peroxides aspolymerization initiators and accelerators.

EXAMPLE 23 An air-drying unsaturated polyester resin is manufactured ina known manner by condensation of 306 g. of fumaric acid, 133 g. oftetrahydrophthalic anhydride, 368 g. of diglycol and 113 g. ofpentaerythritoltriallyl-ether in the presence of 0.3 g. of hydroquinone.The mixture of 65 parts by weight of this polyester resin and 35 partsby weight of styrene has a viscosity of approx. 700 cp. at 20 C. and anacid number of 25.

To manufacture a lacquer solution, parts by weight of styrene, 1.5 partsby weight of benzoin-ethyl-ether (a), 0.6 part by weight of triphenylphosphite (b') and 0.2 part by weight of triphenylphosphine (b") areadded to 100 parts by weight of this mixture. When applied to a glassplate at a film thickness of 100 and after a period of irradiation of 30seconds under the mercury vapor high pressure lamps described in Example1, and subsequent cooling to room temperature, this lacquer solutionyields a non-tacky, highly glossy film.

The above result is surprising because an appropriate mix free ofphosphite and free of phosphine has only very unsatisfactory storagestability in the dark especially at higher temperatures up to about 60C., and it does not gel under UV-irradiation conditions described incomparison tests 1 to 31 even after irradiation times of about 120seconds.

EXAMPLES 24-31 The procedure of Example 10 is followed, but adding 5parts by weight of further copolymerisable vinyl compounds, as indicatedin Table 7, and 1.5 parts by weight of benzoin-isopropyl-ether insteadof the benzoin-ethylether (parts by weight relative to 110 parts byweight of mixture A).

TABLE 7 Gelling Example time in No. Copolymerisable vinyl compoundsseconds Methyl methacrylate.

- Isobutyl methacrylate 17 26 Butyl methaerylate 17 27- ButanediollA-dimethacrylate 23 28 Triethylene glycol dimethaerylate 17 29Vinyltnlnan e 18 30 Chlorostyrene 16 31- p-Tert.-butylstyrene 18 12increased so that cured films having better solvent resistance areobtained.

The conjoint use of p-tert.-butylstyrene according to Example 31 gives adecreased polymerization shrinkage and herewith an improved bondstrength of the cured coatings.

EXAMPLE 32 110 parts by weight of the mentioned mixture B yet withoutaddition of paraffin, are admixed with 1.5 parts by weight of benzoinbutylether (a), 0.6 part by weight of triphenylphosphite (b') and 0.2part by weight of triphenylphosphine (b"). This mixture is applicated toa cleaned and ground sapelli mahogany plywood using an amount of g./m.and it is irradiated 30 seconds under the conditions described inExample 21.

On top of this UV priming a polyester coating lacquer made of parts byweight of mixture B (with addition of paraffin), 1.5 parts by weight ofbenzoin-ethyl-ether (a), 0.6 part by weight of triphenylphosphite (b')and 0.2 part by Weight of triphenylphosphine (b"), 0.75 part by weightAerosil (I-IDK, Type V15), 0.3 part by weight silicon fluid PL (1% byweight solution in toluene) and 30 parts by weight butylacetate is beingapplied in a wet film thickness of about 300 and it is irradiated bysuperactinic fluorescent lamps (Philips, TLM W/OS RS) at a distance of20 cm. after an exposure to air of 30 minutes.

The endcuring takes place within 30 seconds in the UV-light curingtunnel as described in Example 21 after the flooding of the wax. Havingbeen cooled to room temperature the coating is ground and mop-polished.

A highly glossy lacquering is obtained having excellent fillingproperties and an outstanding adhesion to the substratum.

EXAMPLE 33 By condensing 750 g. propanediol-1,2, 587 g. maleic anhydrideand 578 g. tetrachlorophthalic anhydride an unsaturatedself-extinguishable polyester resin is produced in a known manner andstabilized using 136 mg. hydroquinone and 68 mg.p-tert.-butylpyrocatechol.

A mixture containing 65 parts by weight of the above polyester resin and25 parts by weight styrene and 10 parts by weighttrichloroethylphosphite shows a viscosity of 1400 cp. at 20 C. and anacid number of 28.

100 parts by weight of this mixture are admixed with 1.5 parts by weightbenzoinpropylether (a), 0.6 part by weight triphenylphosphite (b') and0.2 part by weight triphenylphosphine (b"). Using this composition twoglass-fibre mats with a customary synthetic resin binder based onpolyester and having a 'Weight per unit area of 450 g./m. are laminatedsuccessively onto a polished aluminum sheet the surface of which issupplied with a release agent. After the mats are impregnated by theabove described composition the laminate is covered by a transparentsheet the surface of which is supplied with a release agent and then thelaminate is exposed to the mercury vapor high pressure lamps for secondsas being described in Example 21.

After cooling to room temperature the sheet can be pulled off and thelaminate can be separated from the aluminum plate. By this manner aflame resistant and self-extinguishable, glass fibre-reinforced, plateis obtained having good transparence.

EXAMPLES 34-37 100 parts by weight of a polymerisable mixture consistingof 67 parts by weight of polyester resin (manufactured from 2 mols ofmaleic anhydride, 1 mol of phthalic anhydride and 3.08 mols ofpropanediol-1,2) and 33 parts by weight of styrene, stabilised with0.014% by weight of hydroquinone, and having a viscosity of approx. 1100cp. at 20 C. and an acid number of 30, are diluted with a further 10parts by Weight of styrene and with 0.5 part by weight of a 10% strengthby weight solution of paraffin (melting point 5253 C.) in toluene, inorder to manufacture a coating composition.

Benzoinphenylether (a), triphenylphosphite (b') and triphenylphosphine(b") are added to this mixture in the concentrations indicated in Table8. These solutions are poured on a glass-plate giving a layer about 1mm. thick and were exposed to the irradiation of a UV lamp (El-Vak,Luminotest, Elektro-Vakuum-GmbH, Berlin) at a distance of 17 cm. Thegelling times are indicated in Table 8.

The gelling times that have been ascertained under same conditions ofthe mixture free of phosphites and free of phosphines are indicatedadditionally for comparison.

I See footnote at bottom of Table 1.

A mixture according to Example 34 was applied to a glass plate in alayer 400,11. thick and was then exposed to irradiation of asuperactinic fluorescent lamp (Philips TL-M 120 W/05 RS) until the filmgelled. After an additionnal exposure time of 45 sec. in a UV curingtunnel as described in Example 21 a nearly colorless cured film isobtained after cooling to room temperature.

EXAMPLES 3 8-40 By condensing 306 g. fumaric acid, 133 g.tetrahydrophthalic anhydride, 368 g. diglycol and 133 g.pentaerythritoltriallylether in the presence of 0.3 g. hydroquinone anair-drying unsaturated polyester resin is produced in the known manner.The mixture of 65 parts by Weight of the above polyester resincontaining 35 parts by weight of styrene has a viscosity of about 700cp. at a temperature of 20 C. and an acid number of 25.

In order to manufacture a lacquer solution 100 parts by weight of thismixture are mixed with parts by weight styrene.

Benzoinphenylether (a), triphenylphosphite (b'), and triphenylphosphine('b") are mixed with the above mixture in the concentrations indicatedin Table 9. Exposing to the UV lamp (El-Vak, Luminotest, Elektro-Vakuum-GmbH, Berlin) the gelling times, indicated in Table 9, are obtained.

For comparison the gelling times that have been ascertained under sameconditions of the mixture free of phosphites and free of phosphines areindicated additionally.

TABLE 9 1 See footnote at bottom of Table 1.

A lacquer solution of Example 38 being applied to a glass plate in afilm strength of 1001:. gives a non-tacky scratch resistant, highlyglossy film, after an exposure time of 30 sec. in a UV light curingtunnel as described in Example 21 and cooling to room temperature.

14 EXAMPLE 41 A modification of Example 21 is made in that 20 parts byweight of an air-drying polyester resin is admixed additionally withmixture B without addition of paraffin as described in Example 23.

Such a roller filling composition can be abraded much better aftercuring, even in the hot state.

EXAMPLE 42 A mixture obtained according to Example 34 but by usingbenzoin-p-tert.-butylphenyl-ether instead of benzoinphenylether wasapplied to a glass plate in a layer. 400g thick and was then exposed toirradiation of a superactinic fluorescent lamp (Phi-lips TL-M W/OS RS)until the film gelled. After an additional exposure time of 45 sec. in aUV curing tunnel as described in Example 21 a nearly colorless curedfilm is obtained after cooling to room temperature.

EXAMPLE 43 room temperature.

EXAMPLE 44 A mixture obtained according to Example 34 but by usingbenzoin-o-cresylether instead of benzoinphenylether was applied a glassplate in a layer 400,14 thick and was then exposed to irradiation of asuperactinic fluorescent lamp (Philips TL-M 120 W/05 RS) until the filmgelled. After an additional exposure time of 45 sec. in a UV curingtunnel as described in Example 21 a nearly colorless cured film isobtained after cooling to room temperature.

EXAMPLE 45 A modification of Example 32 is made in thattri-ptoluylphosphine is used instead of triphenylphosphine. After curinga highly glossy lacquering is obtained having excellent fillingproperties and an outstanding adhesion to the substratum.

EXAMPLE 46 A modification of Example 21 is made in thattri-ptoluylphosphite is used instead of triphenylphosphite. After curinga filler is obtained that can be abraded excellently.

The employed benzoinarylethers (a) correspond to the overall formulawherein Ar means an aromatic radical.

FURTHER TESTS T 0 THE ADVANCE IN THE ART Test series A A laminate wasproduced from the coating composition C having a portion of 40% byweight of glass silk fabric and was light polymerized.

From the obtained light polymerized laminate the bending strength, thetensile strength and the impact resistance were determined.

15 The following results were received:

Bending strength, DIN 53452 kp./cm. 3150 Tensile strength, DIN 53455kp./cm. 2920 Impact resistance, DIN 5 345 3 kp. cm./cm. 95

Test series B In an analogous manner another light polymerizedcomparison laminate was produced the coating composition C of which didnot contain triphenylphosphite and triphenylphosphine.

The following test values were obtained:

Bending strength, DIN 53452 kp./cm. 3200 Tensile strength, DIN 53455kp./cm. 1850 Impact resistance, DIN 53453 kp. cm./cm. 87

Test series C Bending strength, DIN 53452 kp./cm.

Tensile strength, DIN 53455 kp./cm. 1290 Impact resistance, DIN 53453kp. cm./cm. 110

Moreover all test plates made of the laminate Were tempered at 60 C. for2 hours whereby they became homogenized.

All mentioned test values are average values of test pieces of eachseries.

These test values show that the usual classical cold curing processusing peroxide and accelerators gives products having low bendingstrength and low tensile strength and a relatively high impactresistance. The high value of the impact resistance test can probably bederived from the fact that the remaining content of monomers in thislaminate being cured in the usual manner is higher than in anunsaturated polyester resin being cured by UV irradiation.

It can be clearly seen that the light curing process using benzoinethersonly as photo initiators according to test series B gives considerablyimproved values of bending strength and impact resistance while thetensile strength is slightly decreased compared to the laminate obtainedby the cold curing process according to test series C.

Furtheron these tests show that for light polymerized laminates havingthe overall combination of benzoinethylether, triphenylphosphite andtriphenylphosphine as photo initiator according to test series A verygood bending strength and the best tensile strength were obtained. Alsothe impact resistance is distinctly improved compared to the lightpolymerized polyester containing only benzoinethylether as photoinitiator.

The comparison tests show additionally that by this invention unexpectedimprovements of the light polymerized laminate can be obtained invarious directions.

The coating composition C being used for the above test series was madeas follows:

Coating composition C 100 parts by weight of a polymerizable mixtureconsisting of 67 parts by weight of a polyester resin (produced from 2moles maleic anhydride, 1 mole phthalic anhydride and 3.08 molespropanediol-(l,2)) and 33 parts by weight styrene stabilized by 0.014%by weight hydroquinone and having a viscosity of 100 cp. at 20 C. and anacid number of 30, are diluted using further 5 16 parts by weightstyrene for the manufacture of an impregnating composition.

For the production of a photo-polymerizable mixture parts by weight ofthe above mixture, 1.5 parts by Weight benzoinethylether, 0.6 part byweight triphenylphosphite and 0.2 part by weight triphenylphosphine aremixed. 4

In further test series D and E test pieces were produced from apolyester resin (without glass silk reinforcement).

For the manufacture of test plates 100 parts by weight of apolymerizable composition consisting of 67 parts by weight of polyesterresin (made of 2 moles maleic anhydride, 1 mole of phthalic anhydrideand 3.08 moles propanediol-(l,2)) and 33 parts by weight of styrenestabilized by 0.014% by weight hydroquinone and having a viscosity ofabout 1100 cp. at 20 C. and an acid number of 30, were produced.

Test series D Test plate 1.-For the production of a 1 cm. thick testplate 1 the above mentioned polymerizable mixture was supplied with 2parts by weight methylethylketoneperoxide (50% by Weight) and 0.3 partby weight cobalt octoate (1% by weight Co).

The mixture was arranged between 2 aluminum plates the surface of whichwas covered with a release agent and subsequently cured and tempered at100 C. for minutes in a drying cabinet. From this plate test bars wereout having the size 120 x 15 x 10 mm.

Test series E Test plate 2.-For the production of the 1 cm. thick testplate 2 the above polymerizable mixture was mixed with 1.5 parts byweight benzoinethylether, 0.6 part by weight triphenylphosphite and 0.2part by weight tri' phenylphosphine. This mixture was then placedbetween 2 window glass plates (3 mm. thick) and exposed to the noon sunfor one hour under a cloudless sky and afterwards additionallypost-cured from each side in a UV light curing tunnel under mercuryvapour high pressure lamps for 15 minutes.

From this plate test bars were cut in the above mentioned size.

The following table gives the mechanical test values:

These tests show that the light polymerized polyester resin producedaccording to this invention (according to test series E) has verydistinctly improved values of bending strength, modulus of elasticityand impact resistance compared to a polymerized polyester resin producedby cold curing (according ot test series D). Also these results giveunexpected etfects not to be foreseen.

It will be obvious to those skilled in the art that other changes andvariations can be made in carrying out the present invention withoutdeparting from the spirit and scope thereof as defined in the appendedclaims.

What is claimed is:

1. A method for the production of molded articles, impregnations andcoatings from mixtures, curable by UV irradiation and stabilized, ofunsaturated polyester resins, which are obtained by polycondensationfrom t p-unsaturated dicarboxylic acids or their anhydrides withpolyhydric alcohols employed in a molar excess, and copolymerisablemonomeric compounds. and photoinitiators by molding, impregnating orcoating and sub sequently curing by irradiating with radiation of wave-17 length between 3000 and 800 A., the improvement comprising employingas the photo-initiator an overall combination consisting of (a) 0.1 to 4percent by weight of benzoin-ethers, and (b) 0.1 to 20 percent by weightof organic esters of phosphorous acid of general formula wherein R R andR can be identical or different and represent aliphatic, cycloaliphatic,aromatic, araliphatic or heterocyclic radicals-but one of the radicals RR or R must always be an aromatic radical-and (c) 0.05 to 2 percent byweight of organic derivatives of phosphine of general formula wherein RR and R, can be identical or different and represent aliphatic,cycloaliphatic, aromatic, araliphatic or heterocyclic radicalsbut one ofthe radicals R R or R must always be an aromatic radicaland theprecentages by weight mentioned relate to the total weight ofunsaturated polyester resin and copolymerisable monomers.

2. Method according to claim 1, characterized in that as (a) benzoinethers of primary or secondary alcohols, individually or mixed, arepresent.

3. Method according to claim 1, characterized in that the polyesterresin present is an air-drying polyester resin which contains built-inresidues of ,Byy-unsaturated etheralcohols.

4. Method according to claim 1, characterized in that the benzoin-ethers(a) are present individually or mixed with one another, in amounts of0.1 to about 1.5% by weight, in combination with compounds of trivalentphosphorus (b) and (c).

5. Method according to claim 1, characterized in that the esters ofphosphorous acid (b), containing at least one aromatic radical, whichare present are triphenyl phosphite, tri-p-toluyl phosphite,tris-nonyl-phenyl phosphite and didecyl-phenyl phosphite, individuallyor as a mixture.

6. Method according to claim 1, characterized in that 1 the organicderivatives of phosphine (c), containing at least one aromatic radical,which are present are triphenylphosphine, tri p toluyl phosphine,diphenyl-methylphosphine, diphenyl ethyl phosphine,diphenyl-propylphosphine, dimethyl phenyl phosphine,diethyl-phenylphosphine, dipropyl phenyl phosphine,divinyl-phenylphosphine, divinyl-p-methoxy-phenyl phosphine,divinylp-bromophenyl-phosphine, divinyl-p-toluyl-phosphine,diallyl-phenyl-phosphine, diallyl p methoxyphenyl-phosphine,diallyl-p-bromo phenyl phosphine or diallyl-ptoluyl-phosphine,individually or as a mixture.

7. Method according to claim 5, characterized in that the esters ofphosphorous acid (b) are present in amounts of 0.1 to 2.0% by weight,relative to the total weight of unsaturated polyester resin andcopolymerisable monomers.

8. Method according to claim 1, characterized in that the most preferredoverall combinations, consisting of benzoin-ethers of primary orsecondary alcohols (a), esters of phosphorous acid (b) which onlycontain aromatic radicals, such as triphenyl phosphite or tri-p-toluylphosphite, and organic derivatives of phosphine (c) which only containaromatic radicals, such as triphenylphosphine or tri-p-toluylphosphine,are present.

9. Method according to claim 1, characterized in that small quantitiesof customary accelerators are also presem.

10. Method according to claim 1, characterized in that UV-absorbers arepresent as light stabilisers.

11. Method according to claim 1, characterized in that as (a)benzoinarylethers are present having the overall formula 11 II (I) 0wherein Ar means an aromatic radical.

12. Method according to claim 1, wherein part of the a,;8-unsaturateddicarboxylic acids employed for forming the unsaturated polyester resinis replaced by o-phthalic, isophthalic or terephthalic acid,tetrahydrophthalic or hexahydrophthalic acid, tetrachlorophthalic acid,hexachlorendomethylene-tetrahydrophthalic acid,endomethylene-tetrahydrophthalic acid, adipic or sebacic acid, dimerisedlinoleic acid or soya oil fatty acid or their anhydrides individually orin mixture.

13. Method according to claim 1, wherein the mixtures of unsaturatedpolyester resins, copolymerisable mono meric compounds andphoto-initiators contain additionally polymerisation initiators, metalaccelerators, paraffin, wax or wax-like substances individually or as amixture.

14. Method according to claim 13, wherein in the presence of paraffin,wax or wax-like substances the curing is carried out in a two-stepprocess by firstly pre-gelling under the action of fluorescent lamps ofcomparatively low energy and thereafter the final curing is carried outthrough irradiation with mercury vapor high pressure lamps or byapplication of heat.

15. Method according to claim 1, wherein the copolymerisable monomericcompounds are selected from the group consisting of styrene,vinyltoluene, p-tert.-butylstyrene, divinylbenzene, vinylacetate,vinylpropionate, acrylic acid esters, methacrylic acid esters, methylacrylate, ethyl acrylate, n-butyl acrylate, Z-ethylhexyl acrylate,methyl methacrylate, ethylene glycol dimethacrylate and its higherhomologues, diethylene glycol dimethacrylate and triethylene glycoldimethacrylate, diallyl phthalate, diallyl maleate, diallyl fumarate andtriallyl cyanurate individually or as a mixture.

16. Coatings on timber, timber-like materials and metals when preparedaccording to the method of claim 1.

17. Impregnations for the manufacture of fiber-reinforced plasticarticles when prepared according to the process of claim 1. e

18. Moldings when prepared according to the process of claim 1.

19. Molding, impregnating and coating compositions, curable by UVirradiations and stabilized, of unsaturated polyesters resins which areobtained by polycondensation from a,/3-unsaturated dicarboxylic acids ortheir anhydrides with polyhydric alcohols employed in a molar excess,and copolymerisable monomeric compounds and photo-initiatorscharacterized in that they contain, as the photo-initiator, an overallcombination consisting of:

(a) 0.1 to 4 percent by weight of benzoin-ethers, and

(b) 0.1 to 20 percent by weight of organic esters of phosphorous acid ofgeneral formula PORz ORa

wherein R R and R can be identical or different and represent aliphatic,cycloaliphatic, aromatic, araliphatic, or heterocyclic radicals-but oneof the radicals R R or R must always be an aromatic radicaland 19 20.(c) 0.05 to 2 percent by weight of organic derivatives isationinitiator, metal accelerators, paraflin, wax or waxof phqsphine ofgeneral formula like substances, individually or as a mixture.

R v References Cited 1 (H) 5 UNITED STATES PATENTS a 3,450,612 6/1969Rudolph 204-15923 wherein 1 2 a 3 can be identical or dlfierent3,531,282 9/1970 Miller et al. 204-15923 and represent aliphatic,cycloaliphatic, aromatic, 3,547,633 12 1970 Rust 204 159 24 araliphaticor heterocyclic radicalsbut one of the radicals R R or R must always bean aromatic 1O MURRAY TILLMAN, Primary Examiner radicaland thepercentages by weight mentioned relate to the total weight ofunsaturated polyester TURERASslStam Exammer resin and copolymerizablemonomers. 20. Molding, impregnating and coating compositions V accordingto claim 19, containing additionally polymer- 11713-31: 204-15923:159-24

